When a stranded session window's bounded auto-retry gives up (gateway
resume RPC + REST fallback fail through all MAX_RESUME_RETRIES attempts),
the loader latched forever. Add a $resumeExhaustedSessionId atom armed at
the give-up point so the chat view swaps the perpetual spinner for an
explicit error state + manual Retry button. Retry / reconnect / reselect
clears the latch and resets the auto-retry counter for a fresh cycle; a
route-change away from the stranded session also clears it.
Distinct from $resumeFailedSessionId (armed during the backoff window) so
the error UI only appears once auto-recovery has actually given up, not
mid-retry. Adds i18n strings across en/ja/zh/zh-hant and 3 tests covering
latch-arms-on-exhaustion, stays-clear-while-retries-remain, and
clears-on-route-change.
Austin Pickett
253bfc0e3d